Center plate fan wheel and shaft construction

ABSTRACT

A center plate fan wheel and shaft assembly having two stub shafts secured to opposite sides of the center plate, with each stub shaft end adjacent the center plate being enlarged and hollowed to form enlarged diameter ring shaped shaft end mounting flanges thus providing a ring of thermal and mechanical contact at the center plate, and with each side of the center plate being provided with a countersunk ring surface in which the shaft flanges are seated, and with fastening bolts extending through the flanges and center plate.

United States Patent inventor Joseph H. Hoffman Norwood, Mas.

Appl. No. 1,389

Filed Jan. 8, 1970 Patented Aug. 31, 1971 Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

CENTER PLATE FAN WHEEL AND CONSTRUCTION 3 Claims, 2 Drawing Figs.

US. Cl 416/184,

Int. Cl Fold 5/04 Field of Search 416/95, 185, 184, 244

References Cited UNlTED STATES PATENTS 2,065,7l6 l2/l936 Leonard 416/184 FOREIGN PATENTS 5,880 3/1909 England 416/244 Primary Examiner-Martin P. Schwadron Assistant Examiner-Clemens Schimikowski A!lorneys-F. H. Henson and F. E. Blake ABSTRACT: A center plate fan wheel and shaft assembly having two stub shafts secured to opposite sides of the center plate, with each stub shaft end adjacent the center plate being enlarged and hollowed to form enlarged diameter ring shaped shaft end mounting flanges thus providing a ring of thermal and mechanical contact at the center plate, and with each side of the center plate being provided with a countersunk ring surface in which the shaft flanges are seated, and with fastening bolts extending through the flanges and center plate.

PATENTEB was] 1911 dim FIG.

WITNESSES INVENTOR JOSEPH H. HOFFMAN Maw. M

ATTORNEY CENTER PLATE FAN WHEEL AND SHAFT CONSTRUCTION CROSS REFERENCE TO RELATED PATENT APPLICATIONS So far as is known this invention is not related to any presently copending patent applications.

BACKGROUND OF THE INVENTION There is an increasing demand for large fan rotors for applications where both high temperature gradients and rapid rates of temperature change are encountered and these conditions pose obvious stress, distortion and alignment problems.

PRIOR ART Applicant is not aware of any prior disclosures of a center plate fan wheel and shaft construction similar to the present invention.

SUMMARY In accordance with the invention, the center plate fan wheel and'shaft assembly is comprised of a center plate wheel and two stub shafts. In order to maintain reasonable temperature gradients through the shaft ends adjacent the center plate, such shaft ends are enlarged in diameter and hollow bored for a distance above, the length of the shaft to provide flange end rings for thennal and mechanical contact with the center plate.'The depth of the hollow boring'as referred to above facilitates a desired temperature distribution or gradient across and along the shaft portions adjacent the center plate. Prestressed bolts are passed through the flange ends of the stub shafts and the center plate to secure the assembly. In one form of the invention, each side of the center plate is provided with countersunk ring surfaces to receive the shaft flange ends and in a preferred form of the invention, the enlarged hollow bored end of each stub shaft extends for at least a distance beyond the adjacent peripheral edge of the fan wheel.

Further objects, features and the attendant advantages of the invention will be apparent with reference to the following drawing and specification.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation partly in section of the fan wheel and shaft assembly of the invention; and

FIG. 2 is an end view partly cut away in section to show one form of center plate fan wheel blade for which the wheel and shaft assembly of the invention is suitable.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing the fan wheel generally shown at is comprised of a center plate 11 having a plurality of fan blades such as shown at 12 and 13 and side plates 14 and 15.

The shaft assembly for the fan rotor is comprised of first and second stub shaft members 20 and 21 having enlarged diame ter ends 22, 23 leading to flanged end surfaces 24, 25 respectively. Each enlarged diameter end 22, 23, is hollow bored at 26, 27 so that the flange ends 24, 25 are essentially ring surfaces for thermal and mechanical contact with the adjacent central ring surfaces of the center plate 11. Thus, an enlarged ring for a defined thermal and mechanical contact between the center plate 11 and the stub shafts 20 and 21 is provided to minimize stresses and distortions in the shaft ends and to provide a minimum temperature gradient through the walls 28, 29 of the respective stub shafts 20, 21.

The stub shafts 20 and 21 are secured to each other and center plate 11 by a plurality of prestressed bolts such as shown at 30 to extend through the respective shaft flange ring ends 24 and 25 and suitable apertures such as the aperture 31 in the center plate 11. It is preferred that the bolts 30 be formed of a material having properties to minimize stress relaxation at elevated temperatures and such a material could be a nickel cobalt chrome steel known by the trade name Refractalloy.c In one form of the invention, each side of the center plate 11 may be provided with countersunk ring surfaces 32 and 33 in which the ring flange ends 24 and 25 of the respective stub shafts 20 and 21 are secured. It will also be noted that, in the preferred form of the invention being described, the hollow bores 26, 27 for the respective enlarged diameter ends 22, 23 of the stub shafts 20, 21 extend axially from the center plate for a distance beyond the adjacent peripheral edges 34, 35 of the fan rotor, thus providing additional desired temperature gradients through the material of the respective stub shafts 20, 21 to minimize undersired distortion and expansion of the respective shafts due to high temperature gradients and rapid temperature change rates for the fan rotor center plate 11.

Various modifications will occur to those skilled in the art.

I claim:

1. A'fan rotor and shaft assembly comprising, a first stub shaft, a second stub shaft, a fan wheel having a center plate, and bolt means connecting a stub end of said first shaft to a stub end of said second shaft with said shafts positioned on opposite sides of and the bolts extending through said center plate, said center plate being substantially continuous throughout except for bolt holes through which said bolt means extend, said stub ends of each of said shafts adjacent the center plate being enlarged in diameter and hollow bored to provide a flange ring of thermal and mechanical contact with said center plate.

2. The invention of claim 1 in which each side of the center plate is provided with countersunk ring surfaces in which the flanges of the adjacent stub shafts are seated.

3. The invention of claim 1 in which the enlarged diameter hollow bored portion of each stub shaft extends from the center plate at least beyond the adjacent peripheral edge of said rotor. 

1. A fan rotor and shaft assembly comprising, a first stub shaft, a second stub shaft, a fan wheel having a center plate, and bolt means connecting a stub end of said first shaft to a stub end of said second shaft with said shafts positioned on opposite sides of and the bolts extending through said center plate, said center plate being substantially continuous throughout except for bolt holes through which said bolt means extend, said stub ends of each of said shafts adjacent the center plate being enlarged in diameter and hollow bored to provide a flange ring of thermal and mechanical contact with said center plate.
 2. The invention of claim 1 in which each side of the center plate is provided with countersunk ring surfaces in which the flanges of the adjacent stub shafts are seated.
 3. The invention of claim 1 in which the enlarged diameter hollow bored portion of each stub shaft extends from the center plate at least beyond the adjacent peripheral edge of said rotor. 